Thermodynamic model for the analysis of calorimetric data of oligomeric proteins.
The thermodynamic parameters for the process of protein unfolding can be obtained through differential scanning calorimetry. However, the unfolding process may not be a two-state one. Between the native and the unfolded state, there may be association or dissociation processes or the formation of an intermediate state. As a consequence of this, the precise interpretation of the calorimetric data should be done with a specific thermodynamic model. In this work, we present two general models for the unfolding process of an oligomeric protein: N n right harpoon over left harpoon nN right harpoon over left harpoon nD (model A) and N n right harpoon over left harpoon I n right harpoon over left harpoon nD (model B). In model A, the first step represents the dissociation of the oligomer into the monomeric native species, and the second step represents the denaturation process. In model B, the first step represents the conformational change of the oligomer, and the second step represents the dissociation of this species with the concomitant unfolding process. A canonical ensemble was employed to describe these systems, by considering that the total protein concentration remains constant. In the present work, we show and analyze the behavior of these systems in different conditions and how this analysis could help with the identification of the unfolding mechanism experimentally observed.
Burgos
Inés
I
Departamento de Quimica Biologica, Centro de Investigaciones en Quimica Biologica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Argentina. inesburgos@fcq.unc.edu.ar
Dassie
Sergio A
SA
Fidelio
Gerardo D
GD
D002151:Calorimetry; D008956:Models, Chemical; D055503:Protein Multimerization; D055550:Protein Stability; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics
D011506:Proteins